Chicago: A court here on Thursday will announce the quantum of punishment for Pakistani-American David Headley, a key plotter in the deadly 2008 Mumbai terror attacks staged by Pakistan based terror group Lashkar-e-Toiba (LeT).
US federal prosecutors have sought 30 to 35 years in prison for Headley, who has pleaded guilty to his role in the 26/11 attacks that killed 160 people.
Headley, 52, son of a Pakistani father and an American mother, had changed his given name of Dawood Gilani to scout targets in Mumbai without arousing suspicion.
Ahead of Headley`s sentencing, Gary Shapiro, the acting US Attorney in Chicago, in a memo to the federal district court on Tuesday said that the 30-35 year sentence recommended by the prosecution for Headley was fair.
"While his criminal conduct was deplorable, the uniquely significant cooperation which he provided to the government`s efforts to combat terrorism supports the government`s recommendations," he said.
Headley could receive up to life in prison.
Prosecutors had agreed not to seek the death penalty for Headley in exchange for his plea after he promised in 2010 to cooperate with US authorities.
US Attorney General Eric Holder noted at the time that he had provided extensive "valuable intelligence about terrorist activities".
Headley was the star witness against his Pakistan-born boyhood friend Tahawwur Rana, who was sentenced last week to 14 years in prison for aiding an abortive LeT plot to attack Danish newspaper Jyllands-Posten for publishing cartoons of Prophet Muhammad.
In his Tuesday memo, Shapiro said "Headley played an essential role in the planning of a horrific terrorist attack." He "not only worked at the direction of Lashkar-e-Toiba for years, but also with members of al Qaeda."
"Undeterred by the shocking images of death and destruction that came out of Mumbai in November 2008, Headley travelled to Denmark less than two months later to advance a plan to commit another terrorist attack," he added.
But the information that Headley provided following his arrest and in subsequent proffer sessions was of substantial value to the government and its allies, India in particular, in its efforts to combat international, prosecutors said.
"In addition to providing insight into the personnel, structure, methods, abilities and plans of Lashkar, Headley took active steps to further the investigation into other terrorists.
"Headley`s cooperation assisted the government in filing criminal charges against at least seven other individuals, and his testimony helped to secure the conviction of one co-defendant," it said.
"Headley cooperated with foreign law enforcement, answering questions without restriction from Indian law enforcement over the course of seven full days, and the government expects his cooperation to extend well into the future," the memo said.
(With IANS inputs)